1. Field of the Invention
The invention relates to a method of theft protection of electronic apparatuses connected to a bus system, wherein a signal is triggered when an apparatus is separated from the bus, on the basis of which signal the separation is recognized by the separated apparatus and/or by at least another apparatus in the bus system. The invention also relates to a device for performing said method.
2. Discussion of the Prior Art
Information processing is subjected to an increasing digitization and network connections of processing media. As far as the area of dwellings is concerned, the associated networks are denoted as digital home networks (IHDN: In-Home Digital Network). Televisions, radios, monitors, loudspeakers, cameras, printers, scanners, PCs, telephone services, speech recognition systems, domestic appliance controls, security devices and the like may be integrated in such an IHDN. Based on the usually considerable value of the electronic apparatuses connected to an IHDN, they may run the serious risk of being separated and removed from the bus system by unauthorized persons, i.e. they are stolen. Consequently, there is a need for theft protection of apparatuses connected to the bus system.
A method of theft protection of a computer (client) in a network connection to a main computer is known from U.S. Pat. No. 6,021,493 in which the main computer intermittently sends queries to the computers connected to the network and waits for a reply. In so far as no such reply is received within a predetermined period of time, the main computer assumes that the queried client has been separated from the network and thereupon triggers an alarm signal to the network administrator. This method has the drawback of a constant load of the bus system by the queries of the main computer and the confirmation replies of the computers connected thereto. In so far as this bus load is reduced by correspondingly large time intervals between the queries, the reaction time for recognizing the theft of an apparatus is detrimentally delayed thereby. A further drawback is that the method is centrally performed from the main computer so that an abusive attack on the main computer may destroy the entire security system of the network.